At What Point Does Size Matter?

"We're planning to get back into camping in retirement and travel the great US of A" 12 years ago I made the mistake of listening to comments like those above so started with a 36' DP. Did not take long to learn if a 36' will fit, a 40' will too and then a 42'. Sure it's harder to find a site, but in retirement you do not have to show up Friday looking for a site. Just because a CG say 34' max, there are usually a few that will handle much larger so arrive Monday.
Buy the floor plan and size that is livable and not too big for your truck. The above post has some good advice.